JPH02177373A - Film solar cell - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention uses a colorless and transparent polyimide film as a substrate, and allows light to enter from the substrate side.
The present invention relates to a specific film solar cell that suppresses deterioration of the recon O element and improves charge conversion efficiency, and also improves moisture resistance reliability.

<Conventional technology> Amorphous silicon (referred to as &-St) solar cells can be used as a built-in power source for electronic products such as wristwatches, external power sources for TVs and radios, etc. It is widely used as an auxiliary 1E source such as a bacterial charger for preventing battery discharge, but in recent years it has been used as an external 1E source for thin calculators and FFI bands.

There is a demand for thinner and more quantifiable A-8i solar cells.

Against this background, aluminum plates and stainless steel plates are being considered in place of conventional glass plates as substrates for A-8I solar ponds, but it is important to use F# panels, weight reduction, and flexibility. Since it can be applied, the polymer film substrate is considered M1. As such a polymer film substrate.

Since heat resistance is required, polyimide films such as Kapton are usually used.

However, since the polyimide film described above lacks light transmittance, when the polyimide film is used as a substrate for a tl-a-8i solar cell, it is necessary to have a structure like the second case. That is, a metal electrode 2t- is formed on a polyimide substrate l, and a p-type a-8ICP)m)3
．． Intrinsic a-81(i)-)4. nff1a −
8i (n/-) 5 are sequentially laminated, a transparent electrode 6 is formed on the VC, and a transparent resin layer 7 is further provided to protect the VC surface. Then, entering from the fri transparent resin no side, the original goes in the order of a-8N Nakakura n no → 2- → plea, which becomes VC. The transmission order of this light r
iThis is the opposite of the case with conventional glass plate substrates.

It is known that this is unfavorable in terms of charge conversion efficiency, and that the photodeterioration of t-St becomes large, resulting in a lack of IC reliability.

An attempt has also been made to reverse the formation order of the a-8i layer in ig2 figure V'c and make the likely order P/m→XJil→n, but in this case, a- The quality of the 8t film deteriorates and satisfactory characteristics cannot be obtained.

Therefore, when a normal polyimide substrate is used, since the substrate has poor light transmittance, it is not possible to input the element from the substrate side, and the element must be input from the opposite side.

Ninthly, the current situation is that no custom-made product has been obtained that satisfies the photoelectric conversion efficiency and photodegradation of VC as described above.

So colorless-i! ! clear polyimide film ia-8
It is possible to use it as a substrate for a single-solar pond, and have a configuration as shown in Figure @3. In other words, the exposure electrode 6 is formed on the colorless transparent polyimide substrate 8, and the pll is placed on top of it.

j) -8nI- in order&m1illllL, gold sw on top of it
A t-pole 2 is formed, and a t-pole 1119 is further provided. The structure is as follows. Originally entered from the transparent polyimide substrate side.

In the a-81 skin, the origin goes in the order of p ) 14-$ i layer → n skin. The order in which this light passes is exactly the same as in the case of a conventional glass plate substrate. This eliminates the photodeterioration of the 0a-8i solar cell shown in Figure 2, which causes a decrease in dielectric conversion efficiency, and creates a flexible film solar cell with performance comparable to that of a glass substrate. It becomes possible to obtain .

<Problems to be solved by the invention> However, in a solar cell using a colorless and transparent polyimide film substrate as described in J. Under harsh conditions, such as under high pressure, problems arise in the reliability of solar cells.

As a means to solve such problems, a method of RELing the surface of the polyimide film with a resin having excellent moisture resistance such as an epoxy resin can be considered.

However, in order to avoid the ljt color that accompanies curing, epoxy resin is cured at a relatively low temperature (for example, about 100°C) for a long time (
This is a serious problem due to the difficulty in making confectionery, which requires a film forming process of about 6 hours (for example, about 6 hours). , maku.

There is also the problem of coloring due to changes over time 8 It has a negative impact on photoelectric conversion efficiency 4
There is a fear that it will cause i#.

<Middle stage for solving the problem> Therefore, the present inventors investigated the moisture-resistant and moisturizing skin of a colorless and transparent polyimide film [Q7'j As a result, by providing a fluorine resin no. f
We have discovered that moisture resistance can be improved without impairing scratches, and have now completed the present invention.

That is, 1 the present invention provides a photoelectric conversion element on one side of a colorless and transparent polyimide film substrate, and a VC thickness of 5 to 3 on the other side.
The present invention provides a film solar cell made of 00 μm f, xM permeable fluororesin gold.

A transparent and colorless film is used as the substrate for the film solar cell of the present invention in order to improve the conversion efficiency of the charge conversion confectionery. Thickness of film d Light transmission table, conversion efficiency VC (preferably IL) -
1LILJμ range VCC condition.

If the film does not have a primary thickness of 10μ, the mechanical strength will be insufficient, and pinholes will occur during film production, resulting in poor quality.
It is unfavorable in terms of I'I1m property, and it is
If the thickness exceeds 90, the light transmittance will decrease, the conversion behavior will deteriorate, and the film will become less flexible, which is not desirable.

The above polyimide film is colorless and transparent.

In the present invention, the total light M transmittance is 80% when the thickness is 50 μm.
As mentioned above, those having a yellowness index of 25 or higher are preferably used from the viewpoint of conversion efficiency.

This is a colorless and transparent polyimide film.

General formula below.

The μ barfluor a group is a dimorphonuclear component, which is a meta filler ν and a bara 1 group. ) Shows 2! A polyimide whose main component is a polyimide having a repeating level of IL is used, and such a polyimide can typically be obtained by a reaction between an aromatic tetracarboxylic dianhydride and an aromatic diamine. .

The above-mentioned Kjff group natracarboxylic acid disulfate hydrate is as follows.

3, 3. 4. 4-biphenyltetracarboxylic dianhydride (support), 2,3,3,4-bi7-dilutetoccarboxylic dianhydride, 3+ '#4+'-diphenylsulfonato dicarboxylic dianhydride, 2.2
-bis(3,4-dicarboquinphenyl)heki-fluoroglobanni anhydride, which are early-strength and used in combination.

"f7t, upper dd aromatic cyanide as aromatic dinuclear diamine: 0 m-phenylene diamine m-tolylene diamine, 4,6-dimethyl-m-phenylene diamine, 2,4-diaminomesitylene 4-chloro Examples include -m-phenylene diamine 3,5-diaminobenzoic acid, 5-nitro-m-phenylenethia i7, etc. As aromatic dinuclear diamines, d, 3,3-thia ε Nodiphenyl ether/L/ 3. 3'-diaminodiphenylsulfone, 3°3'-cyabanodiphenyl sulfoxide,
3. 3'-cyaminodiphenylsulfi)',
3. 3'-diaminodiphenylmethane, 3.3'-
Diaminobenzophenone, 3,3'-diaminobiphenyl, 2,2-bis(3-aminophenoxy)hexafluoroglopa 7,2,2-bis(4-aminophenoxy/)
Examples include hexafluoropropane. aromatic 3
Examples of nuclear diamines include l,4-bis(3-aminophenol)benzene, l,3-bis(3-aminophenoxy)benzene, l,4-bis(3-aminophenyl)henzea, and 1.3-bis(3-aminophenyl)benzene. Examples include bis(3-aminophenyl)benzene. Aromatic tetranuclear cyano
Bis[4-(3-7ξnophenoxy)phenyl]sulfone.

Bis(4-(3-aminophenoxy)phenyl)ether, 4.4'-bis(3-aminophenoxy)biphenyl, 2,2-bis(4-(3-azunophenoxy)phenyl)clopane, 2 .2-bis(4-(3-aminophenoquine)phenyl]hexafluoropropane 2.
2-1:'s(4-(4-aminophenoquine)phenyl)hexafluoropropane, etc. These can be used alone or in appropriate combinations.

The polyimide made from the above components has a total transmittance of 2.
The film-forming composition is transparent and has a yellowness index of t-, with a content of at least 80 mol%, preferably r! Therefore, in the present invention, other aromatic tetracarboxylic dianhydrides are preferably included within the range of total light M1 transmittance and yellowness index value 2 and do not significantly reduce photoelectric conversion efficiency. A polyimide film made of sp and aromatic diamine can be used.

As such aromatic tetracarboxylic dianhydride,
Pyromellitic dianhydride, 3,3'-benzophenonetetracarboxylic dianhydride, 4,4-oxycyphthalic dianhydride, 4,4-bis(3゜4-dicarbo7) diphenylsulfone dianhydride things, 2. 3. 6.
7-naphthalenetetracarboxylic dianhydride, l,
2. 5. Examples include 6-naphthalenetetracarboxylic dianhydride, 4,5.8-naphthalenetetracarboxylic dianhydride, and the like. can be used together. "17t, Other aromatic diamines include p-phenylenediamine, 2,5-tolylenediamine, benzidine, and 3,3'-dimethylbenzidine.

4,4-7 aminodiphenyl ether, 3,4-diaminodiphenyl ether, 4,4-cyainodiphenylsulfone s 4,4-cya</diphenylsulfokide,
4,4-7 aminodiphenyl sulfide, 4,4'-diaminodiphenylmethane.

4.4-cyaminobenzophenone. 2,2-bis(4aminophenyl)globan 3,3-cyyitoki7-4,
4-diaminodiphenylmethane 3゜3-dimethyl-4
,4-diaminodiphenylmethane,l,4-bis(4-
7 Minophenoki 7) Benzene 4,4'-Diaminoterphenyl bis[4-(3-Abanophenokicumphenyl] sulfone bis-(4-(4-aminophenoki7)phenyl) ether 4,4-bis(4- Examples include aminophenoxy)biphenyl 2,2-bis(4-(4-azunophenoxy7)phenyl)globan.

These can be used alone or in combination with Chikyu.

The polyimized film serving as the substrate of the film solar cell of the present invention is manufactured, for example, by the following method.

Polyamic acid is synthesized from VC by reacting aromatic tetracarboxylic dianhydride and aromatic cyanide in a medium of M at 80° C. or lower (temperature D).

This polyamide #ll solution tank is used to form a molding body into a desired shape, and the cylinder 7t is placed in air and inert gas in a vacuum.
Polyimide was synthesized by removing the M bath medium and simultaneously dehydrating and ring-closing the polyamic acid under uM conditions of 50 to 350°C. The above polyamic acid was immersed in an anhydrous n-acid/biline mixed bath solution, and the chemical iodization method was carried out during imidization with a demulcent medium. It is also possible to perform V dehydration and ring closure by heating and chemical imidization to form a bolybide.Furthermore, it is possible to convert the polyamic acid solution into a polyimide solution.
It can also be imidized by heating above c. If the resulting polyimide does not have C#4 dissolved in the reaction medium, it will be isolated as a precipitate; 1: When using a polyimide solution, it is mixed in liquid form, so it is either precipitated in a solid medium as in the case of polyamic acid to form a single product, or the polyimide solution is molded into a desired shape. It can also be obtained by removing the organic hexagonal medium under a temperature condition of 50 to 200 V in air or under an inert gas. If it is to be isolated by re-sedimentation, it is necessary to take a lot of precautions.

The above organic bath medium is N,N-dimethylformamide, N,N-dimethylacetamide, diglyme, triglyme, cresol, halogenated phenol methyl celonoldiacetate. Dioxane, tetrahydrofuran, etc. are suitable.

N,N-dimethylacetamide is particularly preferred.

These M machine d media may be used alone, or
More than one may be used in combination. These organic media have a relatively low S point, so the vAvc of imidization that is low in sword heat
This eliminates the problem of decomposition products remaining in the polyimide and causing coloration. N-methyl-2-pyrrolidone is a d-medium that is often used as an m-medium for polyimide.
It is known that it decomposes when heated, and the decomposition* remains in the liquid and causes one color, which is undesirable.

In addition, when using the suitable M machine medium illustrated in the following,
smi such as ethanol, toluene, benzene, xylene and nitrobenzene, colorless transparency of polyimide film? They may be mixed together in one stroke or two or more as long as they are not damaged.

As described in 5 above, when producing colorless and transparent polyamide film gold, the logarithmic viscosity (N) of polyamic acid is

0-59/dHQs in N-dimethylacetamide (rj4 constant at 30°C at 1 degree) is 0.5-5. It is better to prepare silkworms than to be within the tl range! If so. The adhesiveness is preferably 0.7 to 3.0 for long-term use. If the logarithmic viscosity is too low, the mechanical strength of the resulting polyimide film will decrease, which is not desirable; on the other hand, if the logarithmic viscosity is too high, it will be difficult to shape the polyamic acid solution into an appropriate shape. This makes it difficult to spread. It is advisable to set the concentration of the polyamic acid m solution to 5 to 40% by volume, preferably 15 to 30% by volume from the viewpoint of workability.

The above logarithmic viscosity is calculated using the following formula, and the time in the formula is calculated using a capillary viscometer.

When polyamide acid is converted into gold imide to form polyimide in this way, the resulting polyimide has a logarithmic viscosity (3 u℃ at a concentration of 0.5 p/dl in 97% sulfuric acid) from the viewpoint of properties.
(1 constant) It is preferable to set it within the range of t-0.5 to 5.0. A good Mt range is 0.7 to 3.0.

The thus obtained material was cast to a constant thickness on a support with a Vζ finished surface.
At a temperature of 50 to 350 Q, gradually 1c) JD heat is applied to promote the demulsification medium and water extrusion, and the polyamic acid is imidized to obtain a polyimide film. The heating process for removing the organic solvent and imidizing the polyimide film from the polyamic acid solution is performed under vacuum 'F (under M pressure)'! Even if 9 is done under an inert gas atmosphere! If the temperature is between 1 and 2, it is also possible to further heat the resulting polyimide film to 400° C. to make a custom-made polyimide film.

In addition, when using polyimide m liquid, the VC polyimide liquid is cast onto the rζ support in the same manner as described above, and the solvent is removed by heating at a temperature of 50 to 2υO°C. Obtainable. The ninth heating step of such desolvation riA nitride (under reduced pressure) 7?1. may be carried out under an inert gas atmosphere.

Using the colorless and transparent polyimide film obtained by V straining as described above as a substrate, the film thickness is mF! Pond? To get 1
For example, follow the steps below.

First, as a first step, a VC transparent electrode is formed on an S-color transparent polyimide film substrate. An indium-tin oxide film (commonly known as I″rO film) is suitably used for this, but it can be formed by the Group 4 method or the sputtering method VC.The thickness of the transparent electrode is 0.01 to 1 ．．
It is preferable to set it to Llμm.

The desired 4-section property could not be obtained with 0.01μ rumored skin; on the contrary, 1
．． If the layer exceeds 0μ, the transparency decreases by fMl, which is undesirable.

As the second step, the A-811 song, which becomes the former Arashi Hentai element, is added to the transparent 11L best. Form. In addition to the a-8i thin film deposited in the order of p-type → i-type → n-type, p-type a-8iC (amorphous silicon carbide) → i-type a-8t-
Six types of a-8l thin films deposited in the order of +n-type JL-8i can be used.

There are various methods for depositing the a-81, such as sputtering, glow discharge one-component CVD, and ion blating.

For example, in the case of glow discharge, it is heated to a temperature of 200-300°C to form a nine-substrate holder VC0 transparent conductor, which holds a transparent polyimide film substrate.

The substrate holder has 10,000 electrodes, and a VC of 13,56 MHz (supplying Q high frequency power) is connected to the counter electrode.
For example, p-type a-8i#11! To form ij, introduce diborane (,Bz)(a)k into silane, and form n-type a-8j thin 5Ct-VC into silane with phosphine CPH5).
All you need is 4 people. 2. The above-mentioned a-8l film refers to hydrogenated a-8i and fluorinated a-8ik.

As the 3rd CD step, C obtained by using the above method is fi 几a-8.
14 electrodes are formed on the top of the film. The metal polarization includes aluminum, nickel, titanium, chromium, iron, stainless steel, nickel-chromium alloy, etc., and can be formed by an appropriate method such as vapor deposition or sputtering ff1Z.

As part of the W44 process, a-8i/m was fabricated and the metal electrode O was lined with JfBJIYI for the purpose of protection. The resin used for this purpose is not particularly limited, and epoxy resins, urethane resins, acrylic resins, polyiF' resins, etc. are preferably used.

The film solar cell obtained in this way was peeled from the support in water or an organic solvent, and a permeable fluororesin layer was provided on the polyimide film surface. can get.

The light-transmitting fluororesin used in the present invention is 141jVc.

2 QQAim thick jflll shape and the light transmittance at the edge is 9
Has a value of 0% or more, and has properties that are at least equivalent to known fluororesins in terms of abrasive retention, chemical properties, and thermal properties? It is something that you have. When the light transmission force is too low.

The custom-made colorless and transparent polyimide film used for the substrate cannot be used to effectively absorb light, which is undesirable as it leads to a low photoelectric conversion efficiency of F1 as a solar cell.

As a fluororesin with this unique characteristic.

Specifically, examples include "Cytotsubu 6" manufactured by Asahi Glass Co., Ltd. and sold under the black market name.

Methods for applying the fluororesin to the gold polyimide film include, for example, a method in which the fluororesin is dissolved in a m-agent and rubbed with a brush, and a skin method in which 8 rotations are applied.

1 for adoption of printing methods, etc.! , a film thickness is 5 to J1. VC4 pain to become lOμ horse. If the thickness is reduced, the desired moisture resistance effect will not be obtained.
The needle barrel becomes unsuitable due to a decrease in flexibility.

<Effects of the Invention> As described above, since the film thick mt cell of the present invention uses a colorless and transparent polyimide film as a substrate, light can enter from the board side, increasing photoelectric conversion efficiency. , ゛The rapid a-8t/+lC1 element deterioration is also less than that of the conventional film thickness.

Since the primary polyimide film is provided with a specific moisture protection material, it has excellent moisture resistance even after long-term fertilization.

4 Examples> The present invention will be explained in detail below using actual examples.

2. The abbreviations listed in the table below have meanings for the following compounds.

g-BPDA: 3,3; 4,4-biphenyltetracarboxylic dianhydride 6Jl'-1) A: 2,2-bis(3,4-dicarboxyphenyl)hexyl fluoro aglobanni dianhydride 3,
3'-BAPS: Bis(4-(3-Aζnophenoxy)phenyl)sulfone 3,3'-DDS: Bis(3-aminophenyl)sulfone Practical Examples 1-; 1 Comparative Examples 1-2 Moromi Using N,N-dimethylacedothorn as a medium,
0.2 mol, 30% l of the aromatic cyanide and aromatic natracarboxylic dianhydride shown in Table 1! The reaction was carried out at room temperature 'F for 30 hours at a temperature of 11 degrees Celsius to obtain a polyamide fermentation liquid. Logarithmic viscosity of this polyamic acid [t-0,511/di, 3
The results are shown in Table 1. This boria zeta #d solution was cast onto a support to form a liquid film, dried in a hot air circulation dryer at IUfJ℃, and when the amount of remaining #solvent was less than 30%, the heating process was started. and finally 30tl″G
The imidization reaction was completed by heating to a film thickness of 30 μm.
A colorless and transparent polyimide film of duck was obtained.

The total light transmission and yellowness index (YI) of the polyimide film obtained by such V-filtration are shown in Table 1.

This polyimide film substrate has a thickness of so
After forming a magnetic thin film on I'l'041 of u diluted to 5000% with 97 orchid and suiseki
Diborane (jhHs) was diluted to ppm and introduced into the glow release Mt apparatus. And the area nitrogen degree is 0
．． A film with a thickness of 15 υA was prepared by applying 1 lo high frequency power in an atmosphere of 2 Torr and applying 1 g of heat onto the substrate.
A type a-8ij+llll was provided. Subsequently, the same reaction was carried out by introducing only the 7 runs of diluted ice cream described above, and a non-doped film of 500 UA (DI type A-81) was deposited.

Furthermore, 5000PPm rc diluted with hydrogen-diluted silane and water volume was mixed with poor phosphine (PHs) Yc, and Glow Emission 1 was introduced into the apparatus to dope phosphorus.5L) OA n-type a
−si +− was provided. In this way, a p-type film was placed on a transparent S-colored polyimide film substrate via an ITO film.

The element 'rt transformation A-Si metal is formed by i-type and n-type a-Si glands.

Subsequently, C1 was held in a vacuum evaporator, and an aluminum conductive film having a thickness of 0.1 μm was deposited by a conventional evaporation method.

Next, after stealing from the FC location, Eboki 7 was used as a backing material.
Next, protect the aluminum It electrode by coating it with a resin to a thickness of 50 μm.

Next, the solar cell gold was peeled off from the support, and the surface of the polyimide film was coated with transparent fluorine resin (Asahi Glass Co., Ltd.
Print a film with a dry film thickness as shown in Table 1, and dry it to make a thick film.

Obtained fc film thick solar cell 0 electric conversion effect AM f
The source was irradiated from the colorless and transparent polyimide film substrate side using a heating simulator of + 1 OU m W/eA to a constant constant, and the results are shown in Table 1. It was. 65℃/
95% R, HO

Comparative Example 3 Example IGcj? I plotted the film thick #IE pond in the same way except for my friend who did not set up the foot mallet b'dim'.

As is clear from Table 1, the products of the present invention have excellent moisture resistance.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the film solar cell of the present invention. Figures 2 and 3 show 11 of conventional film solar ridges.
Figure 1 is shown. 1.8...Polyimide substrate, 2...Metal electrode 3
~5...a-Sii-16...Transparent polarization, 9.
・．．．．．．．．．．．．．．．．．．．．．．．
TsulAdu Sword Patent Taganjin Nichijo Denko Co., Ltd. Representative Ken Igoro

Claims (3)

[Claims] (1) A film solar cell in which a photoelectric conversion element is provided on one side of a colorless and transparent polyimide film substrate, and a light-transmitting fluororesin layer with a thickness of 5 to 300 μm is provided on the other side. (2) The film solar cell according to claim 1, wherein the polyimide film has a total light transmittance of 80% or more and a yellowness index of 25 or less when the thickness is 50 μm. (3) Polyimide film has a general formula, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ However, R_1 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and R_
2 is 1 in which the aromatic nucleus bonded to the nitrogen atom is meta-substituted
˜4-tetranuclear components, or meta- and para-substituted di- to tetranuclear components containing perfluoro groups. The film solar cell according to claim 1, which is a film mainly composed of polyimide having a repeating unit represented by the following formula.